WO2013064688A2

WO2013064688A2 - Process for preparing an electrochemically activated water-based solution

Info

Publication number: WO2013064688A2
Application number: PCT/EP2012/071842
Authority: WO
Inventors: Heinrich Eckhoff
Original assignee: Lohas Products Gmbh
Priority date: 2011-11-04
Filing date: 2012-11-05
Publication date: 2013-05-10
Also published as: WO2013064688A3

Abstract

The present invention relates to a process for producing an electrolyte comprising the steps of (a) providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts; (b) passing the solution through at least one cathode chamber to obtain a catholyte; and (c) passing at least part of the catholyte through a first anode chamber and subsequently through at least a second anode chamber to obtain an anolyte.

Description

Process for preparing an electrochemically activated water- based solution

The present invention relates to a process for preparing an electrolyte, such as an electrochemically activated water- based solution, and in particular an anolyte solution as well as to the use of such anolyte.

Electrolysis of aqueous liquids comprising one or more alkaline earth or alkali metal chloride salts, usually sodium chloride, carried out in electrolysis cells comprising a separation between anode and cathode, such a diaphragm, to produce an anolyte and a catholyte liquid have been described in numerous publications, like US 5,635,040 and WO 98/13304, and respective electrolysis cells are commercially available.

Anolyte liquids have been used for numerous applications, including the use as an oxidizing agent, a purification agent, disinfectant, etc.

The prior art uses of electrolyte solutions, and in particular anolyte solutions, have been limited by the fact that the electrolyte is not stable in aqueous liquids. There is thus a need to improve the stability of the electrolyte. Moreover, it would be desirable to improve at the same time the performance and efficiency of the obtained water solutions, such as the biocidal activity or oxidation-reduction potential of anolyte solutions .

These objects are solved by a process according to claims 1 to 10. The invention also relates to an anolyte solution according to claim 11, the use of the anolyte according to claims 12 and 13 as well as to product comprising the anolyte according to claims 14 and 15.

In a first aspect, the invention relates to a process for producing an electrolyte comprising the following steps: (a) providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts;

(b) passing the solution through at least one cathode chamber to obtain a catholyte;

(c) passing at least part of the catholyte through a first anode chamber and subsequently through at least a second anode chamber to obtain an anolyte.

As used herein, the term "electrolyte" refers to an aqueous solution comprising free ions and/or free radicals. In particular, the term refers to an electrochemically activated water-based solution, such as a catholyte and/or anolyte solution obtained by an electrochemical treatment of water. Preferably, the electrolyte is an anolyte solution and, therefore, the present invention particular relates to a process for preparing an anolyte solution.

Moreover, the term "anolyte" as used herein refers to an aqueous liquid generated by electrolysis in the anode chamber of an electrolysis cell comprising separated anode and cathode chambers .

In step (a) of the process an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts is provided. Preferably, the solution provided in step (a) comprises sodium chloride. It is also preferred that the concentration of the one or more alkaline earth or alkali metal chloride salt(s), and preferably the concentration of sodium chloride, in the solution provided in step (a) ranges from about 2 to about 20 g/1, preferably from about 2.5 to about 18 g/1, more preferably from about 2.5 to about 6 g/1. It has surprisingly been found that even such low amounts of chloride salts are sufficient to yield effective electrolytes such as effective anolyte solutions having high activity. Due to the rather low amount of chlorides in the starting solution, even the obtained electrolytes such as anolytes are characterized by a low amount of chlorides such as less than 6 g/1, preferably less than 3 g/1, which in turn reduces the undesired corrosive properties of the obtained solutions.

In step (b) , the solution is passed into at least one cathode chamber to obtain a catholyte solution. For example, the solution of step (a) is fed into the at least one cathode chamber by a supply means such as a peristaltic pump. The solution leaving the at least one cathode chamber is referred to the catholyte. In a preferred embodiment, the number of cathode chambers through which the solution is passed is identical with the number of anode chambers used in step (c) . If a plurality of cathode chambers is used, a variety of hydraulic configurations is possible. In general, if more than one cathode chamber is used, the cathode chambers can be connected hydraulically in series or in parallel. According to a preferred embodiment, the solution obtained in step (a) is passed through at least two cathode chambers connected hydraulically in series, as described in e.g. RU 2208589.

In step (c) at least a part of the obtained catholyte solution is passed into a first anode chamber and then the anolyte solution obtained in the first anode chamber is fed into at least a second anode chamber to obtain anolyte solution according to the invention. Thus, at least two anode chambers are connected hydraulically in series. It will be appreciated that any convenient number of anode chambers may be connected together in series.

Hence, an electrolyser comprising one or more electrochemical cells is provided, wherein each cell comprises a cathode chamber and an anode chamber. The cathode chamber and anode chamber are separated by at least one separator, such as diaphragm or membrane like a semi-permeable or ion-selective membrane, preferably a zirconium-aluminum ceramic membrane. Moreover, an electric current source for the electrodes of the anode and cathode chambers is provided. Electrolytic cells for producing an electrolyte, and in particular for producing electrochemically activated water such as anolyte or catholyte, are known from e.g. US 5,635,040. Preferably, the at least one cathode chamber and at least one of the anode chambers cells used in the process according to the invention form an electrolytic cell comprising co-axial cylindrical and rod electrodes separated by the separator, such as a semi-permeable or ion-selective membrane like a zirconium-aluminum ceramic membrane. Preferably, the internal electrode is used as anode, while the external electrode is used as cathode.

In another embodiment, an electrolytic cell for producing the electrolyte such as anolyte solution can comprise three chambers separated by two membranes or diaphragms, namely a cathode chamber separated from a flow chamber which in turn is separated from an anode chamber. In this embodiment, the solution obtained in step (a) above is passed into the central flow chamber. Some ions of solution (a) can pass the semipermeable or ion-selective membranes and can therefore arrive at the cathode and anode chambers, respectively. The anolyte solution obtained according to this embodiment is characterized by a particular low amount of sodium chloride such as less than 6 g/1, preferably less than 3 g/1, more preferably less than 2 g/1, most preferably less than 1.5 g/1. Due to such a low sodium chloride amount the obtained anolyte has reduced corrosive properties which is a further advantage of this embodiment.

In one embodiment, the electrodes used in the present process, and in particular the electrodes of the first and at least second anode chambers, are made from a material which is selected from the group consisting of coated titanium, platinum, doped diamond, metal coated with doped-diamond and mixtures thereof. If the electrode is made from titanium, it is coated with an electrocatalytic active coating. In particular, the electrocatalytic coating can comprise ruthenium oxide, iridium oxide, platinum, platinum oxide or mixtures thereof. Suitable examples of doped diamond that can be used as a solid electrode or a coating material on other materials such as metals include boron-doped diamond. In another preferred embodiment, the material used as anode or anode coating depends on the position of the anode in the anode series. It is particularly preferred that an anode at the end of the anode series, such as the ultimate anode in the anode cascade, is substantially free of ruthenium and/or iridium oxide, but rather is made from platinum or titanium coated with platinum or platinum oxide.

In a further preferred embodiment of the process, the catholyte solution obtained in step (b) is degassed prior to passing it into the first anode chamber in step (c) . Thus, gases such as hydrogen formed in the at least one cathode chamber are removed by common degassing means such as a commonly used gas separator.

According to a particularly preferred embodiment, the process of the invention further comprises

(d) adding a metal salt to the anolyte obtained in step (c) .

The metal salt may be added in liquid or solid form. The metal salt is preferably a metal sulfate. More preferably, the metal salt is selected from the group consisting of sodium sulfate, magnesium sulfate, aluminum sulfate, sodium carbonate, calcium carbonate and mixtures thereof.

Preferably, the metal salt is added to the anolyte solution in amounts suitable for stabilization of the anolyte. The amount of the metal salt in the anolyte solution obtained in step (d) generally ranges from 1 to 50 g/liter, preferably from 5 to 20 g/liter or from 7 to 15 g/liter.

The anolyte solution obtained by the process according to the invention is preferably characterized in that it has a pH between 6 and 8. In a preferred embodiment, the pH of the anolyte is between 6.5 and 7.5.

Moreover, the anolyte solution obtained by the process according to the invention is preferably characterized in that it has an oxidation-reduction potential (ORP) of about 250 mV to about 1,200 mV, preferably 650 mV to about 1,200 mV such as 650 mV to 900 mV. The oxidation-reduction (or redox) potential can be determined using commercially available devices and standard conditions.

Without any limitation to a particular theory, it was surprisingly found that the anolyte obtained in the process of the present invention has an improved stability and activity and can therefore be stored for prolonged periods without suffering a substantial loss of activity such as biocidal activity .

Thus, in another aspect the invention is also directed to an anolyte solution obtained by the process according to the invention .

The aqueous liquids of the present invention like the anolyte solution may further comprise other compounds, including further oxidizing agents, stabilizers, detergents etc. In a preferred embodiment the composition of the present invention further comprises other oxidizing agents, in particular ozone, chlorine dioxide, hydrogen peroxide and/or peracetic acid (peroxyacetic acid or PAA) .

In a further aspect, the present invention provides electrolytes, such as anolyte, comprising further stabilizing compounds, including silicates. The silicates are preferably alkaline earth or alkali metal silicates and can be added in a concentration of 0.01 to 120 g/1 (dry weight of the alkaline earth or alkali metal silicates) . Respective silicates act as pH stabilizer and thus stabilize the above oxidizing agents. According to another embodiment, the electrolyte like the anolyte solution of the invention may comprise zinc in the form of a salt, including zinc sulphate or zinc oxide.

The electrolyte solutions of the present invention can be used as a cleaning agent, a detergent, an oxidizing agent, a disinfection agent or a plant protecting agent. Consequently, the present invention also provides a cleaning agent, a detergent, an oxidizing agent, a disinfection agent or a plant protecting agent that comprises an electrolyte as described above .

In a related embodiment, the present invention provides the use of the electrolytes, and in particular anolytes, as described above as a cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent.

In particular, the anolytes can be used for the cleaning of surfaces in restaurants, hospitals, chemical production plants, production lines for the preparation of foods, beverages, animal feed and/or pharmaceutical production plants, etc. For example, the anolyte solutions of the present invention may be sprayed onto surfaces using techniques for spraying liquid compositions on surfaces that are generally available in the art.

In one embodiment, the electrolytes, i.e. the catholyte solution and/or the anolyte solution, are directly produced prior to their use for the above purposes. Hence, the electrolytes a produced shortly before their use, such as less than 2 hours, preferably less than 1 hour, more preferably less than 30 minutes before their use. Thus, the process according to the invention is according to this embodiment performed directly at the place where the electrolyte is need to be used, such as in a hospital, by means of a portable or hand apparatus . According to a different embodiment, the electrolytes like the anolyte solutions of the present invention are applied to plants as a plant protecting agent. Respective agents exert positive effects on plant growth due to their antimicrobial activity. The electrolytes like the anolyte solutions of the present invention further induce secondary plant metabolites due to a stress reaction of the plant. The metal salt can surprisingly support these effects and the agents of the present invention therefore causes improved plant protection. In this embodiment, the use of magnesium sulfate or zinc sulfate is preferred; the use of magnesium sulfate is particularly preferred.

In one aspect, the plant protection agent further comprises plant nutrients, including trace mineral salts, including salts of boron (B) , chlorine (CI), iron (Fe) , zinc (Zn) , copper (Cu) , molybdenum (Mo) , nickel (Ni) , selenium (Se) , and/or sodium (Na) .

Alternatively, the electrolytes like the anolyte solutions of the present invention can directly be used for human or animal consumption or the preparation of pharmaceutical products and can be incorporated into respective products to be used for this purpose. The invention therefore also provides food, beverages, animal feed and pharmaceutical compositions comprising an electrolyte such as an anolyte solution as described above, as well as the use of the electrolytes for the preparation of these products. As used in the present application, the term pharmaceutical composition comprises orally applied forms (such as tablets, liquids) , intramuscularly or intravenously applied forms (for example liquids) as well as topically applied forms (such as creams, gels, liquids, plaster) . According to a preferred aspect of the pharmaceutical use the electrolytes such as anolytes of the present invention are used for the treatment of wounds, including treatment of wounds by disinfection. If used for human or animal consumption, the electrolytes of the invention will not contain any compounds that are unsuitable for this purpose, such as chlorine dioxide or other strong oxidizing agents.

Finally, the invention is also directed to an apparatus suitable for carrying out the process according to the invention .

In a preferred embodiment, the apparatus comprises a plurality of electrolytic cells as described above. Each electrolytic cell comprises a cathode chamber and an anode chamber. The cathode chamber and anode chamber are separated by a separator, such as diaphragm or membrane. Moreover, the apparatus comprises an electric current source for the electrodes of the anode and cathode chambers. The solution obtained in step (a) is passed through at least one cathode chamber. Then, the obtained catholyte passes at least partly from the at least one cathode chamber into an inlet of the first anode chamber. A further flow path can allow the remainder catholyte (if present) to flow to an outlet. In addition, it is preferred that the apparatus comprises a gas separator to remove the gas from the catholyte prior to pass it into the first anode chamber.

Claims

Process for producing an electrolyte comprising the following steps:

(a) providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts;

Process for producing an electrolyte according to claim 1 further comprising

(d) adding a metal salt to the anolyte obtained in step (c) .

Process for producing an electrolyte according to claim 1 or 2, wherein the anolyte has a pH between 6 and 8.

Process for producing an electrolyte according to claim 2 or 3, wherein the metal salt is present in a concentration of 1 to 50 g/liter of anolyte.

Process for producing an electrolyte according to any one of claims 2 to 4, wherein the metal salt is sodium sulfate, magnesium sulfate, aluminum sulfate, sodium carbonate, calcium carbonate or a mixture thereof.

Process for producing an electrolyte according to any one of claims 1 to 5, wherein prior to step (c) gas is removed from the catholyte obtained in step (b) .

Process for producing an electrolyte according to any one of claims 1 to 6, wherein the at least one cathode chamber and at least one of the anode chambers form an electrolytic cell comprising a co-axial alignment of electrodes which are separated by a semipermeable or ion- selective ceramic membrane.

8. Process for producing an electrolyte according to any one of claims 1 to 7, wherein the electrodes of the anode chambers are made from a material selected from the group consisting of titanium coated with an electrocatalytic coating, platinum, doped diamond, metal coated with doped diamond and mixtures thereof.

9. Process for producing an electrolyte according to any one of claims 1 to 8, wherein the concentration of the chloride salt(s) in the solution provided in step (a) ranges from about 2 to 20 g/1.

10. Process for producing an electrolyte according to any one of claims 1 to 9, wherein the anolyte has an oxidation reduction potential (ORP) of about 650 mV to about 1,200 mV.

11. An anolyte solution obtainable by a process according to any one of claims 1 to 10.

12. Use of an anolyte solution according to claim 11 as a cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent.

13. Use of an anolyte solution according to claim 11 as a cleaning and disinfection agent for the cleaning of surfaces in restaurants, hospitals, chemical production plants, production plants for foods and beverages and pharmaceutical production plants.

14. Cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent comprising an anolyte solution according to claim 11.

15. Food, beverage, animal feed or pharmaceutical composition comprising an anolyte solution according to claim 11.